If the GSTIN is showing as Active on the GST portal but you are unable to generate the e-invoice, please follow the steps below to resolve the concern:
Step 1: Go to the e-Invoice portal and search for the GSTIN under Taxpayer/GSTIN.
Step 2: Enter the required details and click on the Update button to refresh the GSTIN status from the GST Common Portal.
Step 3: Once the GSTIN status reflects as Active, retry generating the e-invoice.